1 /*
2  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #define DEBUG 0
18 
19 #if DEBUG
20 #include <stdio.h>
21 #include <unistd.h>
22 #define print(args...) fprintf(stderr, ##args)
23 #define debug print
24 #define debug_dump dump
25 #define debug_dump_atom dump_atom
26 #define debug_dump_atoms dump_atoms
27 
28 static inline void
29 print_atom_byte(unsigned char c) {
30 	if (c == '\r')
31 		print("\\r");
32 	else if (c == '\n')
33 		print("\\n");
34 	else if ((c < 32 || c >= 127) && (c != '\t'))
35 		print("\\x%02x", c);
36 	else
37 		print("%c", c);
38 }
39 
40 static inline void
41 dump_atom(const struct diff_data *left, const struct diff_data *right,
42 	  const struct diff_atom *atom)
43 {
44 	if (!atom) {
45 		print("NULL atom\n");
46 		return;
47 	}
48 	if (left)
49 		print(" %3u '", diff_atom_root_idx(left, atom));
50 
51 	if (atom->at == NULL) {
52 		off_t remain = atom->len;
53 		if (fseek(atom->root->f, atom->pos, SEEK_SET) == -1)
54 			abort(); /* cannot return error */
55 		while (remain > 0) {
56 			char buf[16];
57 			size_t r;
58 			int i;
59 			r = fread(buf, 1, MIN(remain, sizeof(buf)),
60 			    atom->root->f);
61 			if (r == 0)
62 				break;
63 			remain -= r;
64 			for (i = 0; i < r; i++)
65 				print_atom_byte(buf[i]);
66 		}
67 	} else {
68 		const char *s;
69 		for (s = atom->at; s < (const char*)(atom->at + atom->len); s++)
70 			print_atom_byte(*s);
71 	}
72 	print("'\n");
73 }
74 
75 static inline void
76 dump_atoms(const struct diff_data *d, struct diff_atom *atom,
77 	   unsigned int count)
78 {
79 	if (count > 42) {
80 		dump_atoms(d, atom, 20);
81 		print("[%u lines skipped]\n", count - 20 - 20);
82 		dump_atoms(d, atom + count - 20, 20);
83 		return;
84 	} else {
85 		struct diff_atom *i;
86 		foreach_diff_atom(i, atom, count) {
87 			dump_atom(d, NULL, i);
88 		}
89 	}
90 }
91 
92 static inline void
93 dump(struct diff_data *d)
94 {
95 	dump_atoms(d, d->atoms.head, d->atoms.len);
96 }
97 
98 /* kd is a quadratic space myers matrix from the original Myers algorithm.
99  * kd_forward and kd_backward are linear slices of a myers matrix from the Myers
100  * Divide algorithm.
101  */
102 static inline void
103 dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
104 		 int *kd, int *kd_forward, int kd_forward_d,
105 		 int *kd_backward, int kd_backward_d)
106 {
107 	#define COLOR_YELLOW "\033[1;33m"
108 	#define COLOR_GREEN "\033[1;32m"
109 	#define COLOR_BLUE "\033[1;34m"
110 	#define COLOR_RED "\033[1;31m"
111 	#define COLOR_END "\033[0;m"
112 	int x;
113 	int y;
114 	print("   ");
115 	for (x = 0; x <= l->atoms.len; x++)
116 		print("%2d", x % 100);
117 	print("\n");
118 
119 	for (y = 0; y <= r->atoms.len; y++) {
120 		print("%3d ", y);
121 		for (x = 0; x <= l->atoms.len; x++) {
122 
123 			/* print d advancements from kd, if any. */
124 			char label = 'o';
125 			char *color = NULL;
126 			if (kd) {
127 				int max = l->atoms.len + r->atoms.len;
128 				size_t kd_len = max + 1 + max;
129 				int *kd_pos = kd;
130 				int di;
131 #define xk_to_y(X, K) ((X) - (K))
132 				for (di = 0; di < max; di++) {
133 					int ki;
134 					for (ki = di; ki >= -di; ki -= 2) {
135 						if (x != kd_pos[ki]
136 						    || y != xk_to_y(x, ki))
137 							continue;
138 						label = '0' + (di % 10);
139 						color = COLOR_YELLOW;
140 						break;
141 					}
142 					if (label != 'o')
143 						break;
144 					kd_pos += kd_len;
145 				}
146 			}
147 			if (kd_forward && kd_forward_d >= 0) {
148 #define xc_to_y(X, C, DELTA) ((X) - (C) + (DELTA))
149 				int ki;
150 				for (ki = kd_forward_d;
151 				     ki >= -kd_forward_d;
152 				     ki -= 2) {
153 					if (x != kd_forward[ki])
154 						continue;
155 					if (y != xk_to_y(x, ki))
156 						continue;
157 					label = 'F';
158 					color = COLOR_GREEN;
159 					break;
160 				}
161 			}
162 			if (kd_backward && kd_backward_d >= 0) {
163 				int delta = (int)r->atoms.len
164 					    - (int)l->atoms.len;
165 				int ki;
166 				for (ki = kd_backward_d;
167 				     ki >= -kd_backward_d;
168 				     ki -= 2) {
169 					if (x != kd_backward[ki])
170 						continue;
171 					if (y != xc_to_y(x, ki, delta))
172 						continue;
173 					if (label == 'o') {
174 						label = 'B';
175 						color = COLOR_BLUE;
176 					} else {
177 						label = 'X';
178 						color = COLOR_RED;
179 					}
180 					break;
181 				}
182 			}
183 			if (color)
184 				print("%s", color);
185 			print("%c", label);
186 			if (color)
187 				print("%s", COLOR_END);
188 			if (x < l->atoms.len)
189 				print("-");
190 		}
191 		print("\n");
192 		if (y == r->atoms.len)
193 			break;
194 
195 		print("    ");
196 		for (x = 0; x < l->atoms.len; x++) {
197 			bool same;
198 			diff_atom_same(&same, &l->atoms.head[x],
199 			    &r->atoms.head[y]);
200 			if (same)
201 				print("|\\");
202 			else
203 				print("| ");
204 		}
205 		print("|\n");
206 	}
207 }
208 
209 static inline void
210 debug_dump_myers_graph(const struct diff_data *l, const struct diff_data *r,
211 		       int *kd, int *kd_forward, int kd_forward_d,
212 		       int *kd_backward, int kd_backward_d)
213 {
214 	if (l->atoms.len > 99 || r->atoms.len > 99)
215 		return;
216 	dump_myers_graph(l, r, kd, kd_forward, kd_forward_d,
217 			 kd_backward, kd_backward_d);
218 }
219 
220 #else
221 #define debug(args...)
222 #define debug_dump(args...)
223 #define debug_dump_atom(args...)
224 #define debug_dump_atoms(args...)
225 #define debug_dump_myers_graph(args...)
226 #endif